Neutron-gamma competition for $\beta$-delayed neutron emission

TL;DR

This paper introduces a new microscopic model combining QRPA and Hauser-Feshbach methods to accurately predict neutron and gamma emission probabilities after beta decay in neutron-rich nuclei, accounting for competition effects.

Contribution

The novel QRPA+HF model incorporates microscopic nuclear structure and gamma competition, improving predictions of delayed particle emission in neutron-rich nuclei.

Findings

Gamma-ray competition affects neutron emission probabilities.

Model predicts increased neutron emission near the neutron dripline.

More neutrons emitted on average after beta decay in certain nuclei.

Abstract

We present a coupled Quasi-particle Random Phase Approximation and Hauser-Feshbach (QRPA+HF) model for calculating delayed particle emission. This approach uses microscopic nuclear structure information which starts with Gamow-Teller strength distributions in the daughter nucleus, and then follows the statistical decay until the initial available excitation energy is exhausted. Explicitly included at each particle emission stage is $\gamma$-ray competition. We explore this model in the context of neutron emission of neutron-rich nuclei and find that neutron-gamma competition can lead to both increases and decreases in neutron emission probabilities, depending on the system considered. A second consequence of this formalism is a prediction of more neutrons on average being emitted after $\beta$-decay for nuclei near the neutron dripline compared to models that do not consider the statistical decay.